1. Field of the Invention
The present invention relates to a machine for producing a fiber material web, e.g., a tissue paper web. The machine includes at least one press having a shoe press unit and a drying drum that form an elongated press gap.
2. Discussion of Background Information
German patent document DE-OS 42 24 730, e.g., discloses a machine similar in general to the machine discussed above in which a fiber material web is guided over at least one additional upstream press gap for draining. In this manner, the fiber material web is guided, together with a water resistant or waterproof belt, between two press gaps.
In this regard, shoe press units offer the advantage of effective and volume-preserving drainage, which is of particular significance in the manufacture of tissue papers. While the degree of draining depends on the press impulse as an integral of press pressure over press time, the influence on volume is determined by the maximum pressure in the press zone. In this process, transport from the wire former of the machine through the two press locations is performed with the waterproof belt. While this belt does prevent remoistening of the fiber material web, because of its lack of water absorption capacity, the belt cannot contribute to drainage in the press locations. For this reason, a water-absorbent felt is guided through the upstream press gap. Thus, drainage primarily occurs in this press gap. Therefore, these machines are unsatisfactory not only with respect to their draining performance, but also with respect to cost.